The present invention relates to a press-working steel blanks which are less susceptible to occurrence during press-work of the blanks into various cross sectional shapes, such as, round and square shapes, and a method for producing the same.
Various pressed steel articles of desired cross sectional shapes have hitherto been produced by means of a punch and a die.
However, there has been a problem of ear occurrence in the pressed articles during their press-working from sheet blanks.
The ear is a wavy projection on a pressed article caused by differences in directional properties in the sheet blanks from which it is made. This ear gets larger as the number of press-working stages increases and thus a larger ear is observed in an article obtained by a two-stage press-working than that in an article obtained by a single-stage press-working.
Hitherto now, in the field of press-working of the steel sheet blanks, the occurrence of ears has been regarded as blank unavoidable and the steel blank is prepared in a large size in anticipation of the ear occurrence. This is press-worked and then finally adjusted into a predetermined size.
This conventional preparation method of preparing steel blanks requires using excess portions of a steel sheet which are otherwise unnecessary for the blank, and thus results in a low yield obtained from the steel sheet used for blank preparation and in complicated press-working.